Ceramic coatings are described in U.S. Pat. Nos. 4,248,940 to Goward et al, 4,321,311 to Strangman and 4,676,994 to Demaray. Exemplary ceramics include zirconia stabilized by magnesia, ceria or yttria. Other types of ceramic coatings are also known, and include, for example, Al.sub.2 O.sub.3 and MgO, TiN and Si.sub.3 N.sub.4, and SiC. Ceramic coatings may be used in combination with a metallic coating layer, as discussed in the aforementioned patents, or they may be applied directly to the substrate surface.
The apparatus described by Goward applies ceramic coatings by plasma spray techniques, and the apparatus described by Strangman and Demaray apply ceramic coatings by electron beam-physical vapor deposition techniques.
While the thermal barrier coatings applied using the aforementioned apparatus and techniques have shown some utility in various industries, further improvements are sought for various applications. The present invention satisfies these needs.